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Air pollution from farming and wildfires is more likely to cause dementia

Air pollution, a stealthy danger lurking in our environment, has long been a cause of concern. New research from the University of Michigan emphasizes that no level of it is safe for the brain and has been repeatedly linked to dementia. Alarmingly, specific sources, namely emissions from agriculture and wildfires, might present especially potent threats to our cognitive health.

Historically, many studies have highlighted the nexus between air pollution and its detrimental effects on the brain. Most often, research links it to dementia.

Diving deeper into this topic, environmental epidemiology researchers Boya Zhang and Sara Adar from the University of Michigan’s School of Public Health shed light on the profound impact of certain types of emissions.

Measuring pollution from farms and wildfires

“We saw in our research that all airborne particles increased the risk of dementia but those generated by agricultural settings and wildfires seemed to be especially toxic for the brain,” says Adar, who also holds the position of associate chair of the Department of Epidemiology in the School of Public Health.

With extensive experience, she presently spearheads several major studies focusing on how various pollution exposures affect cognitive aging and dementia.

Adar accentuates the importance of these findings. She said, “Our findings indicate that lowering levels of particulate matter air pollution, even in a relatively clean country like the United States, may reduce the number of people developing dementia in late life.”

The duo’s revealing paper titled, “Comparison of Particulate Air Pollution From Different Emission Sources and Incident Dementia in the U.S.,” finds its place in the Journal of the American Medical Association’s Internal Medicine.

Zhang specializes in studying how air pollution affects cardiopulmonary disease and cognitive aging. He suggests, “This work suggests that particulate matter air pollution from agriculture and wildfires might be more neurotoxic compared with other sources. However, more research is needed to confirm these effects, especially for these two sources which have received less attention in prior research.”

Zhang further stresses the potential significance of this study for policymakers aiming to reduce harmful exposure to air pollution, thereby reducing dementia cases.

What is PM2.5?

As the U.S. is hit with a surge of poor air quality alerts, primarily due to the wildfires in neighboring Canada, public attention has veered towards the minuscule but menacing fine particulate matter, PM2.5.

Measuring less than 2.5 microns, this particulate is tinier than a human hair strand. Its size allows it to breach the defenses of our body. This occurs either by penetrating the brain directly through the nose or crossing the blood-brain barrier. Beyond affecting our respiratory and cardiovascular systems, emerging research underscores its potential harm to cognitive function.

Adar points out, “These findings are quite timely given the increasing frequency of wildfire smoke in our communities.” She warns that aside from immediate health repercussions like throat irritation and breathing difficulties, the smog-filled days might also be imperiling our brain health.

Wildfire smoke, a pervasive stressor, is affecting many U.S. cities, with some witnessing over 30 days of smoky conditions annually. This contributes to an astounding 25% of PM2.5 exposures nationwide and up to 50% in certain western parts.

Connection between pollution and dementia

Built on data from the Health and Retirement Study, which has tracked almost 30,000 adults since 1992, Zhang and Adar’s research found that elevated levels of particulate pollution. This was especially true from agriculture and wildfires, which were highly correlated with heightened dementia risks. These conclusions remained consistent even after considering various other factors.

“With the knowledge of which sources are more toxic than others, it may be possible to design interventions for specific sources as a more effective way to decrease the burden of dementia,” Zhang emphasizes.

Dementia stands as the seventh leading cause of death globally, as per the World Health Organization. This study’s goal was to discern which emission sources are most harmful.

While prior investigations primarily looked at the overall particulate matter in the air, this study took a different approach. Zhang mentions, “In our study, we used a sophisticated prediction model… to estimate the levels of source-specific particulate matter air pollution at participants’ residential addresses.”

In conclusion, while average PM2.5 exposure levels in the study were below the National Ambient Air Quality Standard, the worsening air quality, especially during wildfire events, remains a concern. The implications are clear: It’s not just about immediate health threats; there might be deeper, lasting impacts. And with the ongoing shifts in our climate, these health threats are set to escalate.

More about air pollution and human health

Air pollution is a major environmental risk to health. The contaminants in the air can penetrate respiratory and circulatory systems, damaging the lungs, heart, and brain.

The health impacts of air pollution are wide-ranging, complex, and can lead to both short-term and long-term health problems.

Sources of air pollution

Outdoor air pollution is mainly caused by the combustion of fossil fuels, industrial processes, transportation, and other sources. Indoor air pollution is usually due to household combustion of solid fuels, tobacco smoke, and other sources.

Major pollutants and their impact

Particulate matter is a mixture of extremely small particles and liquid droplets in the air. PM2.5 refers to particles with a diameter of 2.5 micrometers or smaller. PM10 refers to particles with a diameter of 10 micrometers or smaller. PM can penetrate the lungs and enter the bloodstream. This can cause heart attacks, worsen asthma, decrease lung function, and other respiratory diseases. Chronic exposure can lead to more serious conditions like cardiovascular diseases and lung cancer.

Nitrogen oxides (NOx) are emitted from vehicle exhausts and power plants. They can cause respiratory problems, reduces lung function, and can lead to chronic bronchitis.

Sulfur Dioxide (SO2) is produced from the burning of coal and oil. Exposure to SO2 can lead to bronchitis, reduced lung function, and induce asthma.

Ozone (O3) is a major component of smog. Ozone is not emitted directly, but is created by chemical reactions between oxides of nitrogen and volatile organic compounds in the presence of sunlight. O3 can cause or aggravate respiratory diseases, reduce lung function, and cause lung diseases.

Carbon Monoxide (CO) is emitted from vehicle exhausts and incomplete combustion of fossil fuels. CO reduces oxygen delivery to the body’s organs and tissues. High levels can be fatal.

Volatile Organic Compounds (VOCs) are emitted as gases from certain solids or liquids, including paints, cleaning supplies, and vehicle exhausts. VOCs can cause eye, nose, and throat irritation, headaches, and damage to the liver, kidney, and central nervous system.

Heavy Metals (e.g., Lead, Mercury) are emitted from industries, power plants, and some household products. Exposure to heavy metals can cause neurological and developmental damage, especially in children.

Health impacts

Short-term effects include irritation of the eyes, nose, and throat, coughing, shortness of breath, chest tightness, and exacerbation of asthma or bronchitis.

Long-term effects of exposure can lead to chronic respiratory diseases, heart diseases, lung cancer, and can also affect other organs and systems, leading to premature death. It can also affect children’s development, including reduced lung function.

Vulnerable populations

Certain populations are more vulnerable to the health impacts of air pollution. These include children, older people, and those with pre-existing health conditions such as asthma, heart disease, and other chronic conditions.

Recognizing and understanding the health impacts of air pollution is a crucial step towards promoting policies and interventions that can benefit both the environment and human health.

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